Suspension insulator cap



Aug. 30, 1955 E. E. CULBERTSON SUSPENSION INSULATOR v CAP Filed Dec. 12, 1949 2 Sheets-Sheet l ATTORNEY.

Aug. 30 1955 E. E. CULBERTSON SUSPENSION INSULATOR CAP 2 Sheets-Sheet 2 Filed Dec. l2, 1949 FIG. YE

F/G'XIY mwx ATTORNEY.

United States Patent Ofiice 2,716,673 Patented Aug. 30, 1955 SUSPENSION INSULATOR CAP E. Estay Culbertson, Detroit, Mich. Application December 12, 1949, Serial No. 132,576

1 Claim. (Cl. 174-188) The invention relates to caps for high voltage power line suspension insulators and has as its objective the creation of a cap made by practices other than the conventional foundry or sand casting methods.

The present invention makes possible a cap of much lighter weight than previous caps with a relatively high increase in strength of said cap and facilitating accuracy in the controlling of strength or the capacity of each unit;

Eliminates any hazards which may be created in weather-proofing or galvanizing which is a characteristic of malleable ironthe material now generally used;

Provides a means for compensating the difference in expansion and contraction between the porcelain insulating member and the steel skirt where that differonce is greater than normal, due to nature of materials used;

Provides a method for manufacturing a cap in corrosion resistant steel at a price which renders such a unit commercially feasible, creating thereby a cap having greater strength and longer life for installations in areas where atmospheric conditions are unduly destructive to the iron cap now commercially procurable and in general use.

Referring to the drawings:

Fig. I is an elevation partly in section showing a cap comprising a pressed steel skirt member and a forged steel yoke or suspending member, the assembly being eifectuated by swaging.

Fig. II is a fragmentary section showing the details for making the parts shown in Fig. I, and manner of assembling.

Fig. III is a sectional elevation showing a cap assembly formed by crimping the suspending member and skirt members together.

Fig. IV is a fragmentary section illustrating the method employed for eifectuating the assembly shown in Fig. III.

Fig. V is a fragmentary section showing a partial assembly of a cap made by welding the suspending member to the skirt.

Fig. VI is a fragmentary section showing detailed design of elements shown in Fig. V.

Fig. VII is a sectional elevation disclosing a design of skirt using a means within the skirt itself for retaining the porcelain insulating element of the complete insulator assembly.

Fig. VIII is an elevation of the skirt shown in Fig. VII.

Fig. IX is an elevation partly in section of a skirt revealing a means for retaining the porcelain within the cap, employing a beaded band telescoping the body of the skirt to prevent spreading or opening when the insulator is functioning.

Fig. X is a fragmentary view of a structure similar in a general way to Fig. IX except employing a solid ring formed into the skirt at its mouth to prevent spreading.

Fig. XI is a fragmentary view of an embodiment wherein the skirt itself is rolled back into a circumferential head for providing resistance to opening of the mouth under tensional function loads.

Fig. XII is an elevation partly in section of a skirt with a segmental liner comprising means for retaining the porcelain element, not shown, in its assembled relationship with the cap.

Fig. XIII is an elevation partly in section of a skirt with means for compensating the unequal expansion between the porcelain element, not shown, and the skirt, simultaneously providing means for retaining the porcelain and cap in integral relationship.

Fig. XIV-a skirt with conical means at its mouth and method for its securement to the skirt for main- 7 taining the porcelain and cap in integral relation.

As disclosed in the drawings, Figure I is a combination of a forged steel yoke member 1 having an angular groove 2 machined just below the yoke portion for receiving a circular flange 3 in the end of the skirt 4. Using suitable assembling fixtures the yoke and skirt are so placed, relatively, that the flange 3 registers with the groove 2 as shown in Figure II. Suitable tools are then employed for swaging or squeezing the neck 5 of the skirt 4 into the groove with the result as shown in Figure I. The angularity of the groove causes the metal of the skirt to become locked in permanent engagement with the yoke. The galvanizing of the unit for weather-proofing seals the assembly against any possibilities of moisture penetration. A flange 6 is formed at the mouth of the skirt 4 extending inwardly and conically to form a hook for retaining the porcelain insulating element, not shown.

Figure III shows a yoke or suspending element 7 in a crimped relationship with a skirt member 8. The yoke 7 comprising a circularly turned up lip edge 9 (Fig. IV) forming a groove for mating with an inversely shaped groove 10 for permanent engagement, as shown in Figure III. The yoke 7 and skirt 8 are placed in suitable assembling fixtures so that the lip edge 9 of the yoke is forced into the groove 10 of the skirt to effect a permanent conical lock-seam engagement. Galvanizing seals the unit against any moisture penetration.

Figure IV specifically shows the yoke 7 and skirt 8 in their relative positions with each other for assembling and in their respective assembling fixtures.

Figure V shows a yoke 11 in welded relationship with a skirt 12 while Figure VI shows the same parts in their relationship to each other revealing the circular projection 13 on the yoke 11 for concentration of heat for welding.

The parts 11 and 12 when placed in position, as shown in Figure VI, and electric current applied, are then pressed together causing the metal in the circular projection 13 to be fused with that in the flange 14 of the skirt 12. This fusion of metal prevents any possibility of the flange 14 opening up under functional loads which would allow the yoke 11 to pull out. This manner of welding also provides a seal against any moisture penetration without depending upon the zinc coating, through galvanizing, for sealing.

Figures VII to XIII, inclusive, reveal skirt structures made from corrosion-resistant steels. This type of steel is intended for use in tropical salt water areas and also in areas where certain chemical atmospheres render corrosion-resistant materials desirable. In some cases this type of steel is much stronger than ordinary commercial deep drawing steel and obviously may be made of thinner gauge material and, consequently, lighter in weight. Diflerent corrosion-resistant steels react differently to heat and cold, consequently provision must be made to compensate this ditlerence in expansion and contraction when present.

In the type of corrosion-resistant steel commercially known as Allegheny 188, the coefiicient of expansion is much greater than that of the type known as Monel. The Monel rate of expansion and contraction is substantially the same as that of ordinary steel and cast iron and requires no compensating element between the porcelain of the insulator disc and the skirt, but a compensating element is interposed between these same relative members when the skirt member is made from Allegheny 18-8.

Still other steel is available which is not afiected by temperatures up to approximately 400 F. which is considerably higher than atmospheric temperatures and which is substantially for practical applications, nonexpanding at low temperatures.

Current market values of these steels are such that, to attempt to make a comptete cap unit by ordinary casting methods, is commercially impractical. Progress, however, in the electric power distribution field would seem to demand a corrosion-resistant development especially for such areas as previously stated.

In view of this fact, applicant has developed some designs of skirts as shown in Figures XII, XIII, and XIV, in the materials just mentioned, revealing methods for controlling this ditference in expansion and made by stamping processes. In each case the skirts are welded to the suspending element substantially as shown in Figures V and VI.

Specifically, Figure VII shows a skirt element with a series of indentations in its wall 16 for providing means for retaining the porcelain insulating disc element, not shown, while Figure VIII is a picture view of the same skirt showing ribs 17 for tying the side walls 16 into the top flange 18 for strength. This top flange 118 is provided with projections 19 for welding the skirt and suspending elements together, as shown similarly in Figures V and VI.

Figure IX shows a skirt with a telescoping band 20 comprising an unbroken tubularly shaped section 21 for circularly engaging the wall 22 which is so formed as to provide means for retaining the porcelain member in functional relationship with the skirt member. The band 20 being what is known commercially as spot welded at intervals around its periphery.

Figures X and XI are substantially equal in characteristics to Figure IX, the difference being in the nature of the band or bead at the mouth of the skirt, Figure X showing a continuous unbroken band of solid cross section 23 formed against the wall 24 and secured in place by having the end of the wall rolled in conformation therewith.

Figure XI showing the wall 25 so formed at the mouth of the skirt as to provide a hollow circular bead 26 for preventing spreading or opening of the skirt under functional tension loads.

Figure XII shows a correspondingly shaped intermediary member 27 engaging the wall 29 of a skirt and comprising a multiplicity of teats 28 for securing the porcelain element within the cap unit, the member 27 being secured to the wall 29 of the skirt by having the end of the wall inversely formed to provide a circular groove 31 for seating the member 27.

Figure XIII shows a correspondingly shaped member 32 engaging the inner side 33 of the skirt and secured thereto similarly as in Figure XII, and comprising a series of inwardly extending teats 34 for imbedment in the cement, not shown, which is used to secure the porcelain disc, also not shown, within the cap unit. This member 32 is provided with a series of slots alternating in position to form staggered openings 35 at opposite sides of the member 32 for permitting expansion and contraction freely between the skirt and the porcelain element when a steel with a higher coefiicient of expansion is employed.

Figure XIV shows a segmental ring 37 secured to the wall 33 of the skirt by having a shoulder 39 for seating upon an internally formed ledge 40 produced by inversely forming the wall 33 to the inside of the skirt and being secured in place by welding at intermittent points 42, as with projections outwardly extending from the ring. This ring 37 is provided with a tapered side 42 for retaining the porcelain element in functional assembly.

Cap units made in accordance with the design or the present invention are much lighter in weight and stronger to any desired degree than a cap made by ordinary casting or foundry methods, with the elimination of all the hazards inherent in this latter process.

While it is practically impossible to reveal the many varied details which may influence manufacturing methods or alter the physical shape, it is none the less desired to cover the invention through the following claim.

I claim:

A lightweight suspension insulator cap for use with outside electric lines and adapted to seat an insulator encased in bonding cement, comprising a suspending member, a skirt affixed to said suspending member, and a circular liner disposed within said skirt, said liner including a series of alternately opening spaced slots along the edges thereof for compensating the ditference in expansion and contraction characteristics between the skirt and the insulating member, and a plurality of inwardly extending minute projections on said liner to provide a better mechanical bond with the bonding cement and a better distribution of the load on said skirt.

References Cited in the file of this patent UNITED STATES PATENTS page 107, Electrical Engineers Journal. Copy available in 174102 (1). 

